Riley Perry has written a free introductory online book on quantum computing that he described to me as “quantum computing for dummies”.
It’s essentially an undergraduate text, and contains many of the topics (intro to quantum mechanics, basics of the quantum circuit model, Shor and Grover algorithms) that are essential to an understanding of quantum computing, as well as some more advanced topics.
I’ve only thumbed through it, but it looks to present many topics in a very clear and comprehensible way.