Cinco de Mayo is mostly an American thing. Mexicans aren’t all that interested in it.
The Battle of Puebla is a big deal in Puebla, Mexico. The American connection is apparently due to the particular hatred Mexicans in California had for the French around the time of the US Civil War.
It was invented in Los Angeles, CA as a way to have a Mexican Holiday similar to 4th of July to encourage festivals and all that money spending that goes with it.
Pure BS