I think the strangest thing to me about the "four alien species" that have recently been talked about is..
They are all two armed bipeds...
If that is the case it really only leaves two big conclusions that I can think of:
Either it is an optimal evolution form for advanced intelligence (seems less likely)
Or we have a very (like extremely) shared genetic background and similarities across all four (seems most likely)
To me the latter option here has so many more crazy potential options as to why that would be...
Some of the top are; Earth keeps producing intelligent species from it's base genetic makeup and after a new one arises, Earth is soft reset for another to rise.
Panspermia esque and the first intelligent specie was a biped and went around adding it's "intelligence genetics" to various species on other planets.
Time travel and Earth is the back in time that all these species eventually arose from.
Parallel universes with slight divergences on the evolution and these are the ones, so far, that have learned to pass through universes.
I had a few others but these are the top ones I think