Jane Eyre is the title of a novel. The hero of the novel is called Jane Eyre. Can you say "Jane Eyre is the title hero of the novel"? I know that titular hero or eponymous hero is correct, however I'm focusing on the noun+noun phrase here. Any input welcome :-) Thanks!
Title is the noun and titular is the adjective, as you know and (subjectivity warning!) I would encourage using adjectives as adjectives and nouns as nouns*.
There is, however, precedent for using the noun-noun construction.
Since the 1960s use of titular hero has declined while title hero has increased.
This perhaps follows the use of title hero which is far more common than titular character and has been for a long time.
*I would appreciate comment, edit or additional solution which addresses the part of speech of title in title hero. I expect it is not a noun marauding as an adjective, but I am not well enough versed in grammar.