You seem really certain about this-- completely certain. I cant be that certain about it at all given the accounts of credible people and the accounts of the native Americans who were here before us. I don't think the fact that we build cities makes the finding of bones certain, not at all in fact. As I said before, IF the accounts are credible then they would be hiding bones in extremely remote areas that are difficult to reach for humans. Perhaps they grind them down, or eat them, or feed them to animals. We don't typically build cities in the most difficult to reach places anyway. Again ask hunters how often they find the bones of bears who do not hide them--- it is extremely rare and there would be far less bigfoot than bear. IF the reports are credible then we are dealing with a savant of the forest with a high level of intelligence, higher than any animal on this planet save humans. We also may be dealing with a remnant species that is close to extinction. I dont think one can be certain about something like this as you seem to be. I think its fine that you hold the opinion you do but I do not share the certainty.