Wild Picard/BSG crossover: both are in the same universe, cylons are synths, so present-day humans are half synths; and the current war of the Federation on synths is just the next cycle in BSG's timeline.

And the Ancient Humanoids in The Chase either predate the first cycle in BSG, or created the original humans on Earth that Colonists discover in the series ending

S01E08 just reinforced this headcannon.
@Janeway but hownqould that explain the first contact coming to earth, they have to be from a different world.
@quark which first contact? Humans and Vulcans?
@Janeway no I mean the first contact attempt back with Rios' first ship. They compared it to the Cochrane warp drive first contact. The theory is that once a civ reaches a certain level of Synth development they are visited by an envoy from some world of synths.

@quark My understanding was that Rios' first contact was with synths from Maddox's colony (aka Dahj/Soji's homeworld), after the ban. Maddox's synths didn't make contact with that higher civilisation yet.

The only contact with that higher civ we know of is via the Admonition.