Cormen's "Introduction to Algorithms" is a dense textbook on algorithms which probably should've advised the reader to start skimming at some point within the book as eventually it becomes more of a reference manual than anything. Nonetheless, it's my personal top pick for an introductory level algorithms text.
Skiena's "Algorithm Design Manual" is a lot more accessible I'd say, and feels much more like it was meant for self-learners rather than professors to use as schoolbook. I think this would be the best place to start, retrospectively.
https://teachyourselfcs.com/ This is a good website for some CS book recommendations, by the way.