Does the layer inherit the Lambda function's runtime version if I don't choose a compatible runtime when I create the layer?

The compatible runtimes parameter when creating a layer determines which layers are displayed when adding a layer to a function, but does not affect actual layer compatibility. If no compatible runtimes are specified for a layer, Lambda will invoke functions using that layer against any of Lambda's supported runtimes. The "compatible runtimes" property does not enforce true compatibility at the runtime level - it is simply metadata that controls layer discoverability.