Tesla (the company) didn't invent electric cars, but they were the first to make electric cars that people actually wanted to buy.
Pre-Tesla, the public perception of elecric cars was something like this: https://www.youtube.com/watch?v=X2HX5wsQVEA (this did not age well)
They were expensive, small, underpowered, and had poor range. Musk took a weakness (expensive) and turned it into a strength (luxury status symbol) by just embracing that making a high-performance electric car was going to be really expensive and marketing it as a toy for rich people to show off how rich they are. Then, he used the profits from that to scale production and bring down the price for future models.
I don't know if he invented this business strategy, but it's a least a pretty brilliant application of it, along with the admirable goal of reducing fossil fuel emissions by putting more electric cars on the road. He also open-sourced all patents developed by Tesla, so other manufacturers could benefit from whatever they discovered along the way.