Could UFOs simply be beings from different versions of earth?

Im starting to think that in the span of finding nothing out there in space, and all the activity we have here and the mysterys we often get that also play into ancient clans/tribes/etc.

Could ufos of every variant simply be from another version of earth with some being able to traverse dimensions to look for things whilst other aliens of these earth are only just discovering this technology which is why they often crash and which is how the government’s get access to these. maybe the government is doing this because they think its some sort of protection, who wouldn’t feel safe knowing we have no way to safely guard against inter-dimensional aliens from other versions of earth.

I also highly doubt the government is able to properly reverse engineer things, im starting to think maybe the laws of those dimensions are different to ours which is why tech that works in their demension doesent work in ours, hence more info as to why they crash and why we can’t reverse engineer, otherwise I’m certain at this point one country would of already ruled the world after destroying every others nuclear arsenal.