Is there a way to tell if my pumpkin is ripe enough to make baby food with? It's very hard when I cut into it and the inside is a little like spaghetti squash after I've cleaned it out. I have never cooked anything with pumpkin before.
Raw pumpkins are very hard and more or less inedible. They are similar to potatoes: you have to cook them before you can eat them.
Most pumpkin varieties are not as stringy as spaghetti squash, at least their edible portion isn't. The fibers in which the seeds hang are not eaten, you eat the hard part (after cooking it to make it soft). It is also possible that you got the wrong kind of pumpkin - while you can eat pumpkins meant for carving, their texture is not so nice as that of pumpkins grown for food purposes.
Practically all recipes for pumpkin involve creating soft pumpkin purée first, and this must be even more important for baby food. Our user derobert wrote an extensive guide on making good pumpkin purée on our community blog. The basic idea is that you clean and bake the pumpkin, then process the result to a homogenous but watery mass, which is basically already edible. He recommends to dehydrate it to achieve a better tasting product which requires less freezer space for storage. I don't know if the last step is desirable for baby food, maybe the parents around here have an opinion on it.
While an unripe pumpkin would be as hard as a ripe one, I doubt that anybody would sell unripe pumpkins, I have never encountered any, not even at the discounter supermarkets. And even if you should get one which is slightly unripe, I don't think this would be much of a problem. With fruit which is eaten raw, the problem with being unripe is that it is too hard and tasteless for eating. Baking the pumpkin will soften it enough even if it is unripe, and while tasteless pumpkin is unfortunate, it shouldn't upset anybody's digestion, not even a baby's.
If the pumpkin is completely orange (on the outside) and the skin is hard, it's ripe. All squash are somewhat hard to cut.
I recommend slicing it into wedges then roasting after coating in a little oil (grapeseed is apparently the most hypoallergenic) then scraping it off the skin before blitzing it up for baby.