Is there a cognitive bias for ascribing agency to inanimate objects?
Fortunately, some psychologists have looked into it, and in accordance to your observations, people do tend to attribute intentional agency to inanimate objects.

In the seminal work by Heider and Simmel (1944), participants were shown shapes of a triangle and disc moving around a two-dimentional landscape. They were not moving in random directions, but in ways that convinced the participants they were acting, fighting, playing or helping each other. When objects move in a purposeful manner, and not just fall to the ground aimlessly, we naturally tend to think they have intentions, belonging to the kind of beings with some kind of intelligence. See also Barrett and Johnson (2003): The Role of Control in Attributing Intentional Agency to Inanimate Objects.

Further more, this tendency is used by the camp of the skeptics, like Dan Dennet or Steven Pinker, to explain why people recognize many events around them as the actions of of gods or super-natural beings. By coincidence, they see some random event or movement, which has no obvious or natural explanation. The witness of such event looks for the agent behind it, and when one can't be found, it is attributed to a hidden or unseen intentional being. The way from there to gods, deities and religion, these thinkers claim, is very short. See Dennett's BREAKING THE SPELL.