You don't need to blame every file[1]. Use `git rev-list` to find your oldest commit:

  git rev-list --reverse --date-order HEAD | head -1  # or
  git rev-list --reverse --author-date-order HEAD | head -1

To see the files in that commit:

  git ls-tree -lr <commit-id>

To see a particular file:

  git show <commit-id>:/path/to/file  # or
  git cat-file -p <commit-id>:/path/to/file

[1] Caveat: I suppose this doesn't account for files which no longer exist or that have been completely re-written.

https://git-scm.com/docs/git-rev-list

https://git-scm.com/docs/git-ls-tree

https://git-scm.com/docs/git-show

https://git-scm.com/docs/git-cat-file

https://git-scm.com/docs/gitrevisions