Q.   A more massive star has a higher or lower central temperature?
A.   Higher of course - hydrostatic equilibrium demands this.
The P-P Chain reaction rate increases (steeply) with temperature. A higher central temperature means the P-P rate is higher and more energy is released - this means a larger luminosity.
So more massive stars have higher central temperatures which results in higher P-P rates which releases more energy and causes the star to have a higher luminosity. So for stars on the main sequence, more massive stars = higher luminosities
We calculated the lifetime of the Sun as an H-fusion-powered object, but this assumed the entire Sun was pure hydrogen and that ALL the hydrogen could be fused to helium. In fact, by the time that about 10% of the hydrogen is fused to helium, the Sun will change its structure and will no longer be a main-sequence star.
A 10 M has a central temperature of 30,000,000 K and a luminosity of 40,000 L .
We know that the fuel of stars is mass and that the rate of fuel consumption is the luminosity. So a 10 M star would be expected to live 10 times longer based on its extra fuel, but, 1/40000 less long based on its fuel consumption:
|Lifespan ( 10 M )||  =  || 10
||  x  ||Lifespan ( 1 M )||  =  ||0.00025 x Lifespan ( 1 M )|
Similarly a 0.3 M star with 0.01 L would have a main-sequence lifetime that was:
|Lifespan ( 0.3 M )||  =  || 0.3
||  x  ||Lifespan ( 1 M )||  =  ||30 x Lifespan ( 1 M )|
So even though more massive stars have more fuel (mass), they use it up faster (higher luminosity) and so have shorter main sequence lifetimes than the less massive stars.