Why do American history textbooks promote the belief that most developments in world history are traceable to Europe?

You have got to be kidding Jill! Please tell me you were joking or your statement is offensive at best. Most people writing history books are themselves Westerners (not as in American West, but as in American or Western-European), or scholars of Western history; hence they see what they know/are as being more important. I won't go into a history of ancient civilizations but even my seven year old knows that they contributed much that forms the basic technologies that use today. This is an excerpt from Loewen's text:

Instead, they argue for Europe's greatness in transparently psychological terms—"people grew more curious." Such arguments make sociologists smile: we know that nobody measured the curiosity level in Spain in 1492 or can with

authority compare it to the curiosity level in, say, Norway or Iceland in Here is the account in The American Way.

What made these Europeans so daring was their belief in themselves. The people of Europe believed that human beings were the highest form of life on earth. This was the philosophy, or belief, of humanism. It was combined with a growing interest in technology or tools and their uses. The Europeans believed that by using their intelligence, they could develop new ways to do things.