A marriage between honey and barbecue sauce....for example. A marriage of wit and wisdom. A marriage of disparate ideas. The idiots who tried to redefine marriage in the tortured fashion you mention just failed in their effort--and good thing. If you try to add to the definition beyond the concept of a union, you're going far afield.
People, to my view, are homo sapiens. Orcas may be intelligent, sentient, self-actualized beings, but they aren't people. People can be mean, stupid, cruel, dumbass racists--there's nothing "noble" or "better" in the word itself. "People" killed those bible students in the church, and those moviegoers in Aurora, and those young students at Sandy Hook. There's nothing terribly recommending about the word "people," in and of itself.
People can be assholes!
As for sapiens, I regard that more as capacity--the gas tank, as opposed to the gas.
Rather than try to expand the definition of "people" to fit animals, I say, instead, just make room for the doggone animals where appropriate. It's simpler than trying to torture the language.