Maybe a walkthrough mode ("hey, I see its your first time here… click on these things… and you’re done!) would be helpful.
More collapsing sections, collapsed by default (most of the information that is displayed is could be on more of a ‘need-to-know’ basis)
Pictures that highlight on selection (like on the o-ring calculator). Maybe even pictures that you can click on and the fields show up there (at risk of making it feel too much like Microsoft Bob).
https://www.chiefdelphi.com/t/swiss-army-engineer-web-based-transient-first-jvncalc/382852/10?u=thaddeusmaximus
Ideas: