Ansible exists because it makes things idempotent, which is great when you have to do a thing on 1,000 servers because you can just fix the role and re-run it.

Bash can be idempotent but isn’t by default, so you either spend time making and idempotent bash script or you spend time learning Ansible to accomplish the same thing in a reusable way

Many years ago I wrote my own "cloud instance bootstrapper" that would pull a tar off of S3 based on EC2 instance tags / metadata, untar it, then run a script. I never got into Ansible and I hated having to rebuild AMIs for minor changes.