While bitcoin script is a stack language, it doesn't really qualify as Forth as it doesn't allow you to define any new words.
No, Bitcoin Script is not Forth. Bitcoin Script is designed to guarantee termination, so no Turing-complete programming language was permitted. Like BPF, Bitcoin Script doesn't have subroutine definitions or backward jumps, so each opcode executes at most once.
This is like saying JSON is C++.
It's more like saying JSON is Javascript, which it is to a degree.
Were there anything in the crypto space is actually solving a problem is up to your own biases and prejudices. But if you pick one thing as actually trying to solve a real problem, payments over lightning is probably that. Lightning, at its core, is a state machine composed of Forth spend scripts.