To your question:
- It depends on what you mean by "Agile"
- If you want to make sense of "original Agile", read "The Agile manifesto" (2001), it's 2 short pages, we can wait for you to get back.
- Criticisms of modern "agile" are actually the same as the problems that spawned that agile movement in the first place. It has become what it reacted against.
- There are practitioners of OG Agile still around and talking / Writing. Dave Farley for one.
- The scientific method does not need to be replaced, hard no. An experimental, incremental, iterative, learning framework is the way forward. The specific rituals of Jira-based scrum, those could go and not much of value would be lost.
If you're looking for a new framework, are you familiar with the Accelerate book? How about Team Topologies ? The Goal ?