Spoiler
El is Eleven. So there were 10 experiments before her. I have a notion that the monster was actually one of them, created by the govt as a weapon. A mutated person. Maybe the Upsidedown is too -- not quite settled on that -- but what I would guess is that nothing is native to it, which just furthers my idea about the monster.
I also don't think Matthew Modine is dead. Too unceremonious a final shot. The monster, somehow, knows him. Perhaps as "Papa"? Perhaps even as literal Papa?? Maybe that one's a stretch, but sci fi is full of mad scientists who sacrifice their own family for "the greater good" of their ambitions/obsessions. The monster doesn't have to be one of the experiments though obviously, but it'll be interesting to learn more about the first 10 whatever happened to them.
Will is obviously an Alien-style incubator. Was it successful or was he purged? I don't know. But Barb probably went through it (she's wasn't eaten, as far as I could tell). So is there a baby monster out there already?
I also don't think Matthew Modine is dead. Too unceremonious a final shot. The monster, somehow, knows him. Perhaps as "Papa"? Perhaps even as literal Papa?? Maybe that one's a stretch, but sci fi is full of mad scientists who sacrifice their own family for "the greater good" of their ambitions/obsessions. The monster doesn't have to be one of the experiments though obviously, but it'll be interesting to learn more about the first 10 whatever happened to them.
Will is obviously an Alien-style incubator. Was it successful or was he purged? I don't know. But Barb probably went through it (she's wasn't eaten, as far as I could tell). So is there a baby monster out there already?