The Earth is not a planet. The word planet comes from the Greek, planasthai (I believe), to wander. As the Earth does not wander, but stays firmly in place, it is inaccurate to call it a planet. God created the Heavens and the Earth. The Earth is clearly special, being one of the two entities God mentions He created in the first verses of Genesis. Why should the shape of the Earth conform to the shapes of less significant objects God later creates in the Heavens? I might go on safari and see only antelope, but that does not make me an antelope.
In case you haven't realised, a circle is flat. A sphere, however, is spherical.
I'm not saying dogmatically the Earth is flat, but I think this fits the scriptures more easily than a spherical Earth. I don't believe a flat Earth contradicts any scripture.