Haven’t the Philippines and China been fighting over the Spratleys forever?
Not really. Most of this dispute stems back to the mid 1960s when an ocean floor survey estimated that there were significant oil and gas deposits in the Spratleys and between Japan and China. This is largely about energy, national pride, hegemony and security.
In the same way, between 1895 and the mid 1930s China made no claim upon Taiwan, instead calling for its independent liberation, alongside Korea, from Japanese colonial rule. It was when Mao and Chiang realised the strategic importance of Taiwan that they modified party and national constitutions to include a claim on Taiwan, entirely without any form of dialogue or communication with the Taiwanese themselves.