What Are Traces and Spans in OpenTelemetry?

I've been tasked with adding telemetry to an AWS based service at work:

CLI -> Web API Gateway -> Lambda returning a signed S3 URL S3 upload -> SQS -> Lambda which writes to S3 and updates a Dynamo record -> CLI polls for changes

This flow isn't only over HTTP and relies on AWS to fire events. I worked around this by embedding the trace ID into the signed URL metadata. It doesn't look like this is possible with all AWS services.

I wonder if X-Ray can help here?

It can also be tedious to initialize spans everywhere. Aspects could help a lot here and orchestrion [0] is a good example of how it could be done in Go. I haven't found an OTEL equivalent yet (though haven't looked hard).

[0] - https://datadoghq.dev/orchestrion/docs/architecture/#code-in...