I looked at the references but as far as I can see they do not show an exmaple of where the selected rows are inserted at another position given by a Range (or perhaps Rows).
It would be good to know if my $selection statement does what I hoped it would do - that is the equivalent of selecting the rows sepecified.
As another trial I did try

$sheet->Range("A39") = $selection
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but this gave the following error
Can't modify non-lvalue subroutine call at insert_rows.pz line 16.