It is due to the history of our alphabet that the order is the way it is. The Latin script, a variety of which is used in English (alongside many other languages), has evolved over time, much like the languages that use it. The alphabets we commonly use in the West (Latin, Greek, Cyrillic) were ultimately derived from the Phoenician alphabet, which in turn gave rise to many other alphabets such as various Semitic scripts (Hebrew, Arabic) and the Greek alphabet.
The Phoenician alphabet was derived from hieroglyphics and came into being sometime around 1400 BCE. The Phoenicians traded a lot in the Mediterranean, and as a result, they had a lot of contact with a wide variety of peoples, so the Phoenician writing system became fairly well-known to them. The Greeks probably adopted the script sometime around the 8th or 9th century BCE, though it is hard to say when exactly; there isn't evidence of it being present before the 8th century, so it was probably during or after. Over time, they made changes to it -- introducing new letters such as Chi and Psi, making alterations to the shapes and orientations of letters, etc.. These changes ultimately led to what we know as the Greek alphabet, which in turn led to the development of the Latin script.
So if we got our alphabetical order over time, where did the original order come from? It's hard to say exactly why, but we do know that there was an alphabetical order in Phoenician that was more or less retained as it evolved into other systems. Certainly it makes sense why a standard order would exist for organizational purposes, especially for merchants. But ultimately, our alphabet is organized the way it is because of history/tradition.
Sources: