Since Universe is Infinite, it is scientifically impossible to prove non-existence of something. Still people tend to claim of being first at something. America

Since Universe is Infinite, it is scientifically impossible to prove non-existence of something. Still people tend to claim of being first at something. Americans claim they are first humans walked on the Moon. Is it provable? Did they monitor the Moon all the time it's exists? May be there was another civilization of humans which waked all over the Moon centures ago? Did Columbus discovered America? - there were people living on the land! etc. It is all relative, sure.