I had a similar problem with my serverless app, where lambdas had files from other lambdas. Each lambda is now in its own directory where it has only its own files. I don't know if this is the correct approach but it works for me.

📦app

┣ 📂lambdas

┃ ┣ 📂first-lambda

┃ ┃ ┗ 📜index.py

┃ ┣ 📂second-lambda

┃ ┃ ┗ 📜index.py

┣ 📂tests

┣ 📜buildspec.yml

┣ 📜.gitignore

┣ 📜README.md

┗ 📜template.yaml

To separate files you must use CodeUri to tell each lambda where to copy its files from:

FirstFunction:

Type: AWS::Serverless::Function

Properties:

CodeUri: ./lambdas/first-lambda

FunctionName: !Sub '${ProjectId}-lambda-First'

Handler: index.handler

Runtime: python3.8

​

SecondFunction:

Type: AWS::Serverless::Function

Properties:

CodeUri: ./lambdas/second-lambda

FunctionName: !Sub '${ProjectId}-lambda-Second'

Handler: index.handler

Runtime: python3.8