Gonna pull up a leddit article here,am sorry faggots.
Hinata's story is that of overcoming anxiety.
She didn't have any sort of physical symptoms of anxiety such as blushing,stuttering or avoiding eye contact before series as shown in "the last" and "pain arc flashbacks" meaning she developed anxiety after sometime but before series,the reasons are most likely because of Hiashi's strict rules,her burdens and her relationship with Hanabi & Neji.
She never liked hurting others,she was kind,and therefore she lost against Hanabi in the fight for the next Hyuuga clan heir.
Hiashi was disappointed of Hinata,he might have seen her as a little girl with a lack of strong resolve that fits the Hyuga clan heir.
A failure in his eyes,he stopped loving her and gave her to Konoha as she wasn't what he wanted anymore.
Since then Hiashi didn't see Hinata as his own child,just a failed tool for his succession.
Hinata started doubting herself,she developed a lack of self confidence because she wasn't able to keep up with the expectations of her fellow clan members.she also develops an inferiority complex against fellow clan members like Hanabi and Neji.
Hence develops insecurities,her self doubt created anxiety and hence paved her path in depression.
This is where she finds Naruto,a similar kid who is undergoing depression hence is relatable to her.
But Naruto try to put a tough facade and look past it and work hard for recognition,that is what hinata found appealing.without even knowing Naruto had already motivated Hinata.
Begins Naruto the series,she is a quiet and cute girl 12 y/o girl that fits the dere-dere troupe and that admires Naruto.
Time passes and chuunin exams begins,she is met with Neji,depression weakens your pshyche and brings about self doubt,the worst fear in a depressed person is to be judged,Neji uses this to mentally attack Hinata. As a similar person Naruto doesn't like this,so he defends Hinata and motivates her.