Now your separating the game from the world, if we lived in the game, like were playing, you don't think one kanto person, like oak who has some of the books and talks with rowan almost every time on the anime would know or the manga soon would? no, stop it.
You just can't look at that way, game limititation has no way of deciding that, say all the games were made at the same time, arceus could be known to all...who even says sinnoh knows about arceus, not many do. Not many anyone knows about arceus in the game, just the professors and researchers and stuff. Saying kanto has no idea of arceus, and sinnoh knows some of mew...is just looking through how the game were developed, which you can't just look through.
Ok mew was after arceus, Arceus came in a time of chaos before anything, and just chaos, Arceus was the first egg, and thus the first pokemon. Ancestor does not nessarily mean creator, creator and the original one are a whole lot more linked together then that.
There also no proof that Mew never knew/helped out arceus ether. So befor you go all haywire, what proof is there that they didnt? EXACTLY, none, so it could be ether way, we don't know, personally I think there is one, as arceus had to the create mew to create others, so how they didnt have a relationship like that is NOT impossible.
And I can believe as I wish, just a theory, there's no need to shot something like that down. so no period any / either way. period.
OK. I'm the kind of person that speaks with evidence. I share informations when they are supported with proofs. Proofs are the best evidences to say whether your idea is true or false.
When there are no proofs, then it is harmful to say your theory is true, right? You can't convince people to believe in a theory if it doesn't even have a single proof. If you are aware of the ways of the scientific community, then you'll understand. They share hypothesis, theories and other ideas to each other, as long as there are proofs.
I only believe to theories with proofs, solid or not, as long as they are worth believing. There are some theories that doesn't have any support. Those are theories that are not convincing. Sorry, but your Arceus-Mew relationship theory falls in that category. That theory's only an opinion, and I want to emphasize this here. It's harmful to believe in theories with no proofs. Sometimes, it even puts you to danger if you continuosly believe rumors or 'theories' that are proofless. I practice this manner from home, in school, and even to forums. I don't want to make a lot of mistakes, so I collect as many proofs as possible before posting. I collect as many proofs as I can before believing.
1.)
First, I'm not separating the real world from the game world. In fact, I base my ideas in the real world, too. Of course, Prof. Oak and Prof. Rowan always talk, but I don't even think that Prof. Rowan has any idea where can he find this 'Original One', what the 'Original One' looks like, etc...
He might not even know the accepted name of this 'Original One' since the word 'Arceus' hasn't been documented in any ancient texts and has been forgotten. And Arceus only appears in legends, if the Pokemon World is a real world like ours, then it will be harmful to believe in legends. Really, many of the legends of this world of ours are already labeled as 'inspiring stories' instead of insisting that they are true. I don't even think Prof. Rowan personally saw this 'Original One' to go spread the world about the 'Original One' legend. So I'm using common sense here. It's harmful to advertise something that is not proven or seen, and that's why only few are aware of the Original One's legend. The lack of informations about Arceus will result of his legend being abandoned and I'm sure that the professors will set aside the legend.
And do you think the Kanto people, especially the Gym leaders there, had any idea about the legends of the 'Original One'? Absolutely no, as they never opened a topic about that. I'm using common sense here too.
I'll tell you, only the player is aware that Arceus really existed and no one else. That's the reason of the player's efforts to find an Azure Flute and climbing to Mt. Coronet. Eventually, he'll be the one to justify the legend as true, as once he catches or even see a glimpse of this Godlike Pokemon, it will be recorded to his Pokedex. So that's it.
It's the player's mission to prove that Arceus is real, as no one else can. Not even Prof. Rowan. Not even the Elite Four.
2.) It's funny to tell that Mew was after Arceus. Where did you get that idea? There is no proof that Mew is after Arceus.... Arceus is sleeping, according to legends. Sleeping, and nothing else. Arceus will never send any 'eyes or ears' of his because he's sleeping. He needs rest and therefore guarding the world 24/7 by sending 'eyes and ears' is a bad idea.... It will only ruin his sleep. Do you want Arceus to suffer from the effects of sleep deprivation?
It's like the beliefs of Deism. According to Deists, there exists a God that created the world, the universe, and its inhabitants perfectly according to his plans.
BUT, Deists tend to assert that this God does not interfere with human life and the laws of the universe. That's the very nature of Arceus. Creator, and nothing else. Arceus' role is only creator and nothing else. Only Creator. If not, then give me an example of an event where Arceus was interfering with the actions of mankind. I guess not. He's sleeping, and take it literally. He's only the creator, and nothing else. The main and the most popular legend about Pangu tells that Pangu hasn't interfered with human actions after creating the world, unlike the God of Abrahamic religions. Remember that Arceus' legend is based upon Pangu of Chinese myths...
Therefore, sending Mew as Arceus' reporter is a bad idea, I tell you. And I don't think Mew is serving SOMEBODY...... Even the Pokedex will disagree on that theory, because it is hard to think they have a relationship....
3.) OK, tell me what Arceus has created. He shaped the world/universe with his one-thousand arms, created the legendary Pokemons Palkia, Dialga, Mesprit, Azelf, Uxie.... What else? After creating the legends, he slept, right? So, I conclude that Arceus never created Mew, or created other Pokemons. Pokemons traced their genes back to Mew, so Mew was responsible for the existence of the other Pokemons, and not Arceus.
Arceus created the world, the five other Sinnoh legends, and then he slept after that. That's very understandable!!! It only needs common sense. Arceus never created Mew, because it is already documented what he did. The rest, it's not his fault why they existed. He's asleep. Accept it. The 'Arceus created Mew' theory is pure speculation !!!
4.) Do I need an evidence on my ideas? I have one. The absence of documentation about the Arceus-Mew relationship is my VERY PROOF. Haha !!! I use common sense, so if I were you, don't ask questions like 'What's your proof?' to me.
5.) Thanks for sharing your idea, but I guess that your theory was not convincing, unless if the GameFreak or the Pokemon Company announce that they really had a relationship. Let's wait for Arceus' movie, shall we? 
