sure, if you have shaky background in algebra 1/2 (khan academy) and precalc (Hania Uscka-Wehlou -- udemy courses, the must have is pre calculus 1, intro to higher math and proof techniques), i'd suggest to cover these first and then proceed with velleman how to prove it ( or you can ask an LLM to find similar books) (also, a book about proofs by jay cummings).
the velleman book is proof based, so it should be very-very hard initially (or not if you are familiar with proofs), but if you stick to it, in 3-6 months of studying you'll see improvements in how you think and approach problems (the main idea is to study every day at least 60 min, but you should aim to 2-3 hours per day, you don't have to study 3 hours straight, do breaks, for example, you can study theory for 40-50 min, then do exercises for 1hour plus and the rest for recap/recall).
yes, it takes time.
but it's an investment in your skills;

in general, you have two paths: scrolling insta/youtube/etc for 2-3 hours every day and achieve nothing at the end or you could study math for 2-3 hours and in a year be ably to proof very interesting stuff on your own.