Humans are considered monkeys because they belong to the taxonomic family Hominidae, which is a subfamily within the larger family of primates called Hominidae. The Hominidae family includes great apes like chimpanzees, gorillas, and orangutans, as well as humans.
The classification of living organisms, including humans, is based on their evolutionary relationships and similarities in their genetic and physical characteristics. The evolutionary history of primates, including monkeys and apes, can be traced back to a common ancestor. Over millions of years, different branches of primates evolved, leading to the various species we see today.
Within the Hominidae family, there are two subfamilies: Ponginae, which includes orangutans, and Homininae, which includes gorillas, chimpanzees, and humans. Humans are classified under the tribe Hominini within the Homininae subfamily.
So, while humans share common ancestry with monkeys and other apes, we are more specifically classified as hominins, a group that includes modern humans (Homo sapiens) and our extinct relatives, such as Homo neanderthalensis and Homo erectus. Nonetheless, the term "monkey" is often used informally to refer to both monkeys and apes, including humans, as they all belong to the same larger group of primates.