There's been a topic on the Steam discussion board about this. About a third of the replies consist of people screeching about people needing to git gud.
That sounds like fun reading (actually, no it doesn't).
I remember watching someone play through Bloodstained for a bit and hearing her say that she thought she was sequence breaking the game because she got the Aqua Stream early. I guess she thought it was supposed to drop from a boss.
As soon as I got the Aqua Stream, I just used it to progress and rolled with it as though nothing strange happened. The spiked corridors where you needed the Aegis plate on the other hand was the part that tripped me up. It took me a while before realizing I had a thing in the inventory to get past it (the Aegis plate).