odd man in

Often Dante gets inserted in a list/lineage of English poets.

literary lineage

A critic who could take any new poet and show the links to all her/his literary lineage.

line breeder

The lines seemed to breed one after another as though endless in their lineage.

no advancing back

The avant-gardist tries to piece together a lineage/heritage; but one thinks that the forebears he has cited would deny any heirs just as they'd denied ancestors.