What does the Bible say about the nature of humanity?

In 2 Samuel 9:8, Mephibosheth characterizes himself as a 'dead dog' in the presence of King David, symbolizing the humble and desperate state of humanity apart from God's grace. This imagery captures the essence of our fallen nature; we are indeed 'dogs' by nature, unworthy and in need of rescue. Yet, by God's tender mercies, He raises us up through Christ, hiding our shame and granting us dignity at His table, as seen in Romans 8:30, where those He predestines are called, justified, and glorified.