This looks very similar to Amazon Simple Workflow, which has been effectively superseded by Step Functions, which uses static workflow definitions that look very similar to GCP Workflows.
It is similar to the Amazon Simple Workflow as both founders of the Cadence and Temporal projects worked on the Simple Workflow. I actually was a tech lead of it.
I cannot comment on why AWS made certain decisions as I left Amazon soon after SWF launched.
I guess that SWF was hard to use for novices. When developing Cadence and later Temporal, we fixed the majority of rough edges that SWF had. And it turned out that the core "workflow as code" model was something developers love. And with improved developer experience, the adoption is going very strong.
Why do you think AWS moved away from this model?