問這句話該怎麼拆解好呢?我最看不懂的是starting with this natural gift developed by degrees their special aptitudes原文如下?

Sentence Structure:
[main clause] + till (conjunction) [subordinate clause]

1. main clause
subject -> Persons
connective adverb -> therefore
main verb -> developed
direct object -> their special aptitudes
adverbial adjunct 狀語 -> staring with this natural gift - participle phrase modifying the verb "developed" to tell the starting point of action;
adverbial adjunct 狀語 -> by degrees ( 逐漸地) - prepositional phrase modifying the verb "developed" to tell how the action was performed;

2. subordinate clause
subject -> their rude improvisations
verb -> gave
direct object -> birth
indirect object -> to Poetry

"till their rude ...." is also another adverbial (adverb clause) of this sentence to tell the end point of the main verb "developed".