Hi !!
There are two pronouns in this sentence and they both are personal pronouns SUBJECT
-
When he was a small boy, he often attempted to climb the maple tree.
- he was = personal pronoun masc. sing. subject of the verb BE preterit tense (was)
- he attempted = pers. pronoun masc. sing. subject of the verb attempt preterit tense (attempted)
-
☺☺☺