The motto of Sir Francis Drake is:
Sic parvis magna
It is usually translated as "Greatness from small beginnings", but what is the literal translation? Would be be something like "Thus from small things are great things"?
Yes, your literal translation is correct. Both parvis and magna are neuter plural substantive adjectives, which means they're being used as nouns. (Think similarly to our the dead have arisen --- dead is here is an adjective being used as a noun.)
One of the possibilities in translation for neuter substantives is the abstract. See Gildersleeve & Lodge 204.2, which is why the translation has it so.
The skill in making an effective motto is in saying as much as possible in few words (with such few words, big ideas?). So, in addition to all that C.M.Weimer has written there is this.
Sic can also qualify an adjective. So, it can also mean that Drake did not have riches or nobility: starting, materially, in the way of possessions, "with so little, (he achieved) much."
Drake's ship for his circumnavigation was about the length of modern harbour tugs. When he was granted the shield and motto by the Queen, he had just brought back enough treasure to pay the annual expenditure of the Crown, and also pay off his backers (£47 for each pound invested); "with such (sic) small things, mighty achievements."
From 1936 to '48, his ship, The Golden Hind, was the obverse design on the halfpenny. This plays on the Drake motto to encourage taking care of the ha'pennies, so the pounds will take care of themselves. "With such small objects, great things."