Has anyone else needed to break down the movements into the smallest parts before progressing? Anybody else feel their low flexibility is a barrier to be corrected before even beginning lifts?

Noob here, and just yesterday I learned about the 'Hip hinge"

Stronglifts 5x5 were suggested by many people so I have been trying it out. I started by learning the form as best as possible, with no bar, then just the bar, then small weights. Still, it feels uncomfortable in my lower back and I will not increase the load until this is resolved.

After reading the words hip hinge, I followed it on bodybuilding.com and various demonstrations on youtube. Tried them, and discovered I seem to be unusually inflexible. It is difficult to keep a straight back and just lean from the hips. And wing back the elbows is near impossible.