Hey, while Camunda has some similarities on the surface level to Temporal, the way we approach problems is very different.
Temporal is a code-first runtime made by engineers, for engineers. Our biggest focus has been on creating an engine which can scale and serve practically any business use case. Camunda is more focused on enabling developers to surface controls/information to non-technical users in their company. They have put a lot of effort into visual layers for human operators and for composing workflows visually.
In the distant future we plan to either provide these capabilities ourselves, or support community efforts that provide them. Our belief is that if we get the core engine right, we can eventually use it as a foundation to handle everything else.