Why do people constantly refer to the bulk beings as future humans?
I don't accept that the bulk beings are future humans. I believe they are something else entirely and they never originated on Earth.
I believe the bulk beings have always existed in their own realm (outside of time and space) and they have a vested interest in the humans (they actually love the species and realized that the future of the human race was at stake) and that's why they are making sure the humans survive and repopulate in a galaxy far, far away.
So the bulk beings helped the humans by providing them with a wormhole and a tesseract to insure their survival and to prevent extinction of the human race. Bulk beings knew it wouldn't be an easy task for the humans (there would be no challenge by making life easy for them), but it will give the homo sapians a 100% guarantee to survive.
Maybe the bulk beings are the creators of life on Earth. Maybe they are sumkinda super advanced "alien" beings that we call God.
I enjoy watching Interstellar a whole lot more when I reject the idea that the bulk beings are future humans.