Will humans ever colonize Mars?
Yes.... may be
We've been making spacecrafts from much long, those can land on moon, Venus, Earth, Saturn's moon and may be some more....
I won't be dealing with "what would humans do if they reach Mars?" rather "is it possible to go to Mars?"
Mars doesn't promise to be a good planet to land, a spacecraft...
There could be a plenty of ways to land on a planet.
Rockets can be used to land on some planet or moon with less air causing less drag as it makes the spacecraft light in weight because of less use of heat shielding, these spacecrafts can be made from light metals such as Tin
Parachutes can used to land where there is enough drag which can slow down speed of spacecraft. such as our own planet.
But here comes Mars
Mars has an atmosphere due to which heat shielding is required but yet parachutes can't be used to land because of thin air.. So, rockets also have to be used..
Thus reducing success rate of proper landing.
Some balloon like structure could also be used, these might prove better... these spacecrafts would basically jump many times on surface before they successfully land..
Now, it's up to you to figure out that if humans reach Mars will they colonize it or not....