Ackshually...
Erlang didn't introduce the actor model, any more than Java introduced garbage collection. That model was developed by Hewitt et al. in the 70s, and the Scheme language was developed to investigate it (core insights: actors and lambdas boil down to essentially the same thing, you really don't need much language to support some really abstract concepts).
Erlang was a fantastic implementation of the actor model for an industrial application, and probably proved out the model's utility for large-scale "real" work more than anything else. That and it being fairly semantically close to Scheme are why I like it.
The team that built Erlang (Joe, Robert, Mike, and Bjorn) didn't know the actor model was actually a thing. They wanted to build reliable distributed systems and came up with the isolated processes model you find in Erlang today. Eventually (probably when Erlang was open sourced?), folks connected the dots that the actor model was the most accurate description of what was going on!