Tea
The institution of tea has survived over 5,000 years of continuous human consumption. It has outlasted the dynasties that first cultivated it, the empires that fought wars over its trade, and the civilisations that made it central to their cultural identity.
Dried tea leaves, when properly stored, maintain viability for 2-3 years under standard conditions. The practice of tea consumption itself shows no signs of degradation despite millennia of continuous use.
Thanos
As an Eternal-Deviant hybrid, Thanos possesses exceptional individual longevity, having survived for several thousand years. His physical resilience includes resistance to conventional weaponry and the ability to withstand direct combat with beings of considerable power.
However, the historical record indicates two confirmed terminations within a five-year period. The first occurred via decapitation by Stormbreaker; the second through the combined strain of utilising the Infinity Stones. This represents a 100% mortality rate across the documented observation period.
VERDICT
The calculus here proves straightforward. Tea cannot be killed because it was never alive. Thanos, despite his considerable resilience, has been conclusively ended twice. From a durability standpoint, the inorganic nature of processed plant matter provides categorical advantages over even the most powerful organic lifeforms.