This will handle any number of lists at once without destroying the originals. Pass them in by reference and it will return by reference or value, your choice.

sub interleave {
  my @lists = map [@$_], @_;
  my @res;
  while (my $list = shift @lists) {
    if (@$list) {
      push @res, shift @$list;
      push @lists, $list;
    }
  }
  wantarray ? @res : \@res;
}
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