Thankfully its working now !!

Fix #1

You just have to zip ONLY the files and upload it on lambda function else it won't be able to find your file.

Fix #2

I did switch the regions in between which could potentially cause misunderstanding so i deleted existing functions and API gateways and made new one.

Fix #3

I replaced the Access-Control-Allow-Origin: of api gateway from "*" to my deployed URL link.

Fix #4

I increase the Lambda timeout to match or closely align with API Gateway’s 29s limit.