Goddess Saraswati existed before creation as well since she is no different from Adi Shakti, the Ultimate Power. Generally we associated Goddess Parvati with Adi Shakti the most, but Goddess Lakshmi and Saraswati are also the same, they aren't actually three but one just like God Brahma and God Vishnu are no different from Sadashiva in essence. Brahma, Vishnu and Shiva being three forms of One Ultimate Consciousness.
So Maa Saraswati is indeed eternal and always existed.
She then manifested through Brahma in order to assist him in creation, that is why it is said that Brahma created Saraswati, but actually Saraswati is eternal and she manifested through him which makes it appear like that.
Jai Maa Saraswati 🙏