Well lucky for us paragraphs of prose are artistic expression and the snippets of code returned by Copilot are utilitarian.
The only things covered by copyright are creative choices. In software, as established by Whelan v. Jaslow [0] this is the structure, sequence and organization [1].
The district court ruling in the Whelan case drew on the established doctrine that even when the component parts of a work cannot be copyrightable, the structure and organization of a work may be. The court also drew support from the 1985 SAS Inst. Inc. v. S&H Computer Sys. Inc. in which it had been found that copyright protected organizational and structural details, not just specific lines of code. Structure, sequence and organization (SSO) in this case was defined as "the manner in which the program operates, controls and regulates the computer in receiving, assembling, calculating, retaining, correlating, and producing useful information." SSO refers to non-literal elements of computer programs that include "data input formats, file structures, design, organization and flow of the code, screen outputs or user interfaces, and the flow and sequencing of the screens."
However:
The Whelan decision initiated a period of excessively tight protection, suppressing innovation, since almost everything other than the broad purpose of a software work would be protected. The only exception was where the functionality could only be achieved in a very small number of ways. In these cases there could be no protection due to the merger doctrine, which applies when the expression and the idea are inextricably merged. Later the same year, in Broderbund v. Unison the court cited Whelan when finding that the overall structure, sequencing, and arrangement of screens, or the "total concept and feel", could be protected by copyright.
For a brief overview of the merger doctrine:
https://www.lucysnyder.com/index.php/copyright-law-merger-do...
So this excessively tight protection was rectified in CAI Inc v Altai [2], which established the legal doctrine of Abstraction-Filtration-Comparison [3] which says "As we have already noted, a computer program's ultimate function or purpose is the composite result of interacting subroutines. Since each Subroutine is itself a program, and thus, may be said to have its own 'idea,' Whelan's general formulation that a program's overall Purpose equates with the program's idea is descriptively inadequate."
[0] https://en.wikipedia.org/wiki/Whelan_v._Jaslow
[1] https://en.wikipedia.org/wiki/Structure,_sequence_and_organi...
[2] https://en.wikipedia.org/wiki/Computer_Associates_Internatio....
[3] https://en.wikipedia.org/wiki/Abstraction-Filtration-Compari...