I am wondering if AES-128 and the likes were once broken and if they were broken because people knew they were trying to break AES then why don't we create our own personal algorithm to encrypt the data and let the intruders wonder which algorithm was used?
You could create a proprietary encryption algorithm, but to ensure that it is secure you would need to make it public, so it can be properly tested. (bar the secret key obviously).
Security through obfuscation is not recommended. This is the basis of Kerckhoffs's principle.
"The principle goes as follows: A cryptographic system should be secure even if everything about the system, except the key, is public knowledge."
Read more detail here; Kerckhoffs's principle