If you want to learn more about the first transatlantic cable check out How the World Was One by Arthur C. Clarke. Reading it now and really enjoying it: https://amzn.to/3EiACjU
I came to the comments section to make sure this article was posted, it's such a fantastic read. If you read it and are hungry for more, check out "How the World Was One" by Arthur C. Clarke. It's a fascinating history of telecommunications with a large focus on submarine cables.
It does an astonishingly good job of describing how networks evolved and why the function as they do today (as of mid-90's - not much has changed AFAICT).