CORS Issue with AWS Lambda and Ajax - ajax

Question

So I have been working on this serverless configuration that calls a Lambda function through ajax. The I enable CORs through the API Gateway, and I have made sure of the domain I specified. This domain works when calling other lambda functions within the same API.
Now for the weird stuff.
I send a post request (I am trying to upload a file through ajax, lambda, and S3), to my API. If I configure the Access-Control-Allow-Origin so that it points to the domain WITHOUT the http in front of it. Ex: example.com. When I try to call this i get:
Failed to load https://m562ogkc1l.execute-api.us-east-1.amazonaws.com/test/upload: Response to preflight request doesn't pass access control check: The 'Access-Control-Allow-Origin' header has a value 'example.com' that is not equal to the supplied origin. Origin 'http://example.com' is therefore not allowed access.
Ok fine, this is assumed, since that's not the proper domain. So when I add in the http (http://example.com) for the CORs of the API I get:
Failed to load https://m562ogkc1l.execute-api.us-east-1.amazonaws.com/test/upload: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://example.com' is therefore not allowed access. The response had HTTP status code 400.
What this seems like to me is that there is an issue elsewhere, except I don't know where the issue lies.
I have made sure the data I pass for parameters of the ajax call are strignified (JSON.stringify()), and I am NOT running an AWS Lambda Proxy which means I shouldn't be configuring responses on the lambda side of things.
This all really confuses me and I wish AWS had better documentation and examples since they really want to push these serverless services.
Further code is here:
Ajax:
$('#submitButton').on('click', function(){
//console.log(document.getElementById('fileUpload').value.substring(12));//C:\fakepath\ in front of filename (size = 12)
$.ajax({
type: 'POST',
url: 'https://m562ogkc1l.execute-api.us-east-1.amazonaws.com/test/upload',
data: JSON.stringify({"id": id,"name": document.getElementById('fileUpload').value.substring(12),"body": document.getElementById('fileUpload').files[0]}),
contentType: "application/json",
success: function(data){
console.log(data);
//location.reload();
}
});
return false;
});
Lambda:
const AWS = require('aws-sdk');
var s3 = new AWS.S3();
exports.handler = async (event) => {
let encodedImage = JSON.parse(event.body);
let decodedImage = Buffer.from(encodedImage, 'base64');
var filePath = event.id + '/' + event.name
var params = {
"Body": decodedImage,
"Bucket": "repository.example.com",
"Key": filePath
};
return await new Promise((resolve, reject) => {
s3.upload(params, function(err, data){
if(err) {
let response = {
"statusCode": 200,
"headers": {
"Access-Control-Allow-Origin": "http://example.com"
},
"body": JSON.stringify(err),
"isBase64Encoded": false
};
resolve(response);
} else {
let response = {
"statusCode": 200,
"headers": {
"Access-Control-Allow-Origin": "http://example.com"
},
"body": JSON.stringify(data),
"isBase64Encoded": false
};
resolve(response);
}
});
});
};
(Yes I threw in some response configuration for the function, I just wanted to see if it would work)