Was the ark of the covenant really just a rectangular box?
Yes, the ark of the covenant was primarily a rectangular box. It was special, overlaid with gold and had a role to play, but it was not anything other than a rectangular box. The Hebrew word rendered "ark" also means a box or coffin.
Les teaches that the Hebrew word for "ark" is the same word used in the last verse of Genesis and can be translated as a coffin, so an ark is simply a box. It did not necessarily have to have certain dimensions, but according to the Hebrew it was just a rectangular box. When considering the ark of the covenant behind the veil, Les explains it was primarily a rectangular box. It was special, overlaid with gold, and had a role to play, but it was still nothing but a rectangular box. This same basic meaning connects with Moses' ark of bulrushes, which was a rectangular box daubed with slime and pitch, just like Noah's ark instructions. The Hebrew word for pitch is also translated atonement, and atonement is in the blood, making that little box a place of safety—and God is in all this.