Ven. Analayo discusses this in “The Genesis of the Bodhisattva Ideal”
“Being myself subject to old age … and death, now suppose I were to search for what is free from old age … and death, for the unsurpass- able peace from bondage, Nirvāṇa.”23
“Being myself truly subject to old age and death … suppose I were to search … for what is free from old age and death … for the unsur- passable peace from bondage, Nirvāṇa.”24
This appears to be the only passage in the Pāli Nikāyas that explicitly for- mulates what motivated the bodhisattva Gautama to set out in search of awakening. Notably, this formulation does not in any way reflect a concern for others. Rather, according to this autobiographical report the bodhisattva Gautama’s motivation was to find a solution for the problem of being “him self”, attanā/自, subject to old age and death etc. The same trait recurs in the description of the successful completion of the bodhisattva’s quest, given in the Ariyapariyesanā-sutta and its parallel. According to both versions, having arrived at the unsurpassable peace from bondage that is free from old age and death, Gautama realized that he had fully liberated himself from the prospect of future birth and existence. Here, too, there is no reference at all to being able to save others. Instead, the way the Buddha perceived his own awakening – according to early Buddhist discourse – is formulated entirely in terms of having freed him- self.
The conspicuous lack of any concern for others becomes even more prominent with the next episode recorded in the Ariyapariyesanā-sutta, according to which the newly awakened Buddha was disinclined to teach others and decided to rather remain content with having reached liberation himself.
You can read the rest in the link. So, judging from the early texts the Buddha wasn’t motivated to save others. It was to free himself from birth, death and dukkha. This matches this sutta, where we are compassionate because it aids with the goal of freeing ourselves from samsara. Compassion primarily protects us, with others being protected as a by-product:
You protect me, dear Medakathalika, and I’ll protect you. Thus guarded by one another, protected by one another, we’ll display our skills, collect our fee, and get down safely from the bamboo pole.’ When this was said, the apprentice Medakathalika replied: ‘That’s not the way to do it, teacher. You protect yourself, teacher, and I’ll protect myself. Thus, each self-guarded and self-protected, we’ll display our skills, collect our fee, and get down safely from the bamboo pole.’
“That’s the method there,” the Blessed One said
https://suttacentral.net/sn47.19/en/bodhi
Of course, when he became awakened he realised that there were at least some who would get it and so he set out to teach them. That is how we have the sangha today.