Why do we call them "clubs" and "spades" when they look like clovers and pikes?

Because the English names and the pictures come from two different decks. Around 1480, French card makers combined older Latin and Germanic suits into four simpler ones: trèfle (clover), carreau (tile), cœur (heart) and pique (pike). England eventually adopted those French pictures, but the earliest packs circulating there may have had Latin suits, with batons and swords. That probably explains why English speakers call the clover a "club" and the pike a "spade", a word that may come from the Italian suit of swords, spade.

The Latin suits themselves came from the Mamluks of Egypt. A near-complete 15th-century Mamluk pack, found in Istanbul's Topkapı Palace in 1939, originally had four suits: polo-sticks, coins, swords and cups. Its word for a court card, nā'ib, was borrowed into Spanish, Italian and French, and the Spanish naipes is still the everyday word for playing cards.

Cards probably reached Europe through Spain: the earliest European mention is a Catalan rhyme dictionary from 1371. Their pictures changed along the way. Polo was an obscure sport to Europeans, so the polo-sticks became batons or cudgels. In Germanic countries, the Latin suits were replaced with leaves, hearts, bells and acorns, and the French clover probably grew out of the acorn, the pike out of the leaf.

Playing cards themselves are older still. They were most likely invented in China during the Tang dynasty, around the 9th century, thanks to woodblock printing, and in 1294 Chinese officials caught two gamblers playing with paper cards. The story even runs into video games: in 1889, Nintendo was founded to make Japanese karuta cards, most notably hanafuda, and its founder Fusajiro Yamauchi became the largest producer of hanafuda within a few years.