Why does english use so many words from so many languages?
english is several languages blended together.
the rules of english grammar are often inconsistent.
english borrowed words from other languages.

English is originally a combination of languages from three tribes: Angles, Saxons, and Jutes. The three of them moved to England and this resulted to what we know now as the English language. Then, the French came to the country. Latin was made the official language of the clerics. French and Latin words are then added to the language. After which, interaction with other countries (mainly through explorations) made them add more vocabulary for African, Asian, and other European countries. Now, English language borrow words from other languages to name things that don't exist in England. For example, tsunami from Japanese or siesta from Spanish.