The oldest extant Buddhist texts are decidedly Mahayana and there is NO EVIDENCE anywhere that Hinayana/Theravada is older.
The Buddha used different Upayas or skillful means to teach Buddhism to different people, based on their proclivities to understand the Saddharma. However, some Sri Lankan Buddhists (Theravada/Hinayana) claim that the Pali Canon was spoken by the Buddha while the Mahayana came later on. This is a baseless lie and propaganda without any evidence.
“The oldest Buddhist scriptures anywhere in the world are Mahayana as in the Gandhara manuscripts. The Pali Canon is understood to have been written in Sri Lanka, not India. The correct terms used by the greatest Buddhist saints from Kumarajiva and Huen Tsang to even Ambedkar and Nichiren are Mahayana and Hinayana, and so we use the same terminology to uphold authenticity over propaganda.
All texts were written around the same time
All the Buddhist texts -- both Pali of the Hinayana/Theravada and Buddhist Hybrid Prakrit/Sanskrit of the Mahayana were written around the same time -- a few centuries after the physical passing of the Buddha. Also, many themes in one, can be found in the other - without too much deviation or discord. However, the facts are that the oldest manuscripts and Buddhist civilization we find in India, Sri Lanka and of course Japan, China and Korea et all is decidedly Mahayana - thanks to the great Gandharan civilization which boasts the oldest statuary and manuscripts in any museum in the world. Hence, many scholars opine that Mahayana has the tangible traces of the oldest Buddhist civilization on record. Mahayana is also followed by the largest number of Buddhists worldwide. Ideally, Buddhists should choose whether they are Mahayana or Hinayana/Theravada -- but for Theravada to claim it is the "original Buddhism" is a laughable lie and unsubstantiated propaganda. Having studied Buddhist archaeology and scripture, the Mahayana is far more authentic as it encompasses all of us living in the real world -- instead of favoring the few who live in monasteries. Buddhism is for EVERYONE, not just monks - and so Mahayana is the truest path. A society cannot function without teachers, doctors, nurses, policemen, artists et all -- and under Mahayana ALL of them have spiritual potential. The Hinayana was so-called because it EXCLUDES everyone except male monks. Re-branding it as "Theravada" is a ploy to project it as "older or original Buddhism" which it is not. The correct terms used by the greatest Buddhist saints from Huen Tsang to Nichiren and even Ambedkar are Mahayana and Hinayana, and so we use the same terminology to uphold authenticity over propaganda.