Can any kind souls please provide an easily starting point for Aztec Myths and Legends. What I’ve heard of it is interesting, but the sources I can find, I feel, heavily rely on prior knowledge of the readers/viewers. Any online sources would be much appreciated. Merci Beaucoup!
The only book I have is Douglas Gifford's Warriors, Gods and Spirits from Central and South American Mythology (illustrated by John Sibbick). This book is part of the The World Mythology series, which includes books about, well, mythologies from around the world (non-exhaustive, I'd say). The book is not specifically about Aztec myths, but has a whole chapter about them. Note that this series seems to be oriented to a young adult public, so it might be good as a starting point, but not enough if you need something more in-depth.
Native Mesoamerican Spirituality, ed. Miguel León-Portilla, and The Aztecs: A Very Short Introduction by Davíd Carrasco are sources I've used. For the latter source, mythology is addressed mostly in Chapter 4. One note is that most of the primary written sources for pre-Conquest Nahuatl cultures were actually composed post-Conquest, so much of the knowledge that we have is somewhat murky.