Is Aguirre like a real person to you?
No, he doesn't, I guess partly because he doesn't figure very prominently in the story, except of course it's Aguirre who brings them down off the mountain early. I can't understand his attitudes (though I recognise there's plenty of people out there who share his attitudes), in that it's not something I can relate to, so I find it difficult to get inside his head, and therefore he doesn't seem as real to me, not in the same way Ennis and Jack are.
for their child they would adopt? Or Jack would have his son every two weeks??
Jack would have his son every once in a while. I like MAdLori's "Human Interest/Two Crows Joy" fanfics though, where Alma Jnr ends up living with them on their ranch, where she has a good relationship with both of them and Jack treats her as his own daughter, not just Ennis's daughter.