>There are many words in the English language that sound the same though they have been given different meanings. Do you think this is coincidence or intentional? If intentional, for what purpose?

>(examples: world and whirled; I and eye)

I'm going with coincidence. Basically because English is such a mongrel language, we have borrowed and stolen from *everybody*. Meanings and spellings have changed over time.

From the two random examples you gave, *world* is from the Old English *weorold* which is from the Old Norse *verold* ("age of man") but *whirled* comes from the Middle English *whirlen* from the Old Norse *hvirfla* ("turning/revolving/circuit"). 

And *I* comes from the Old English *ic* borrowed from Old Norse *ek* which stole from the Latin *ego*. But *eye* is from the Old English *ege/eage* from Gothic *augo* from the Sanskrit *akshi* and the Greek *opsis* ("a sight").