Final answer:
The poet aligns King Arthur with the founders of ancient civilizations to elevate his status to that of a cultural hero, tapping into collective admiration for great leaders and the universal themes they represent.
Step-by-step explanation:
The poet might have placed King Arthur in line with the founders of ancient civilizations to leverage the timeless appeal and symbolic value of Arthurian legend, aligning Arthur with great historic figures and myths. By doing so, the poet can tap into the collective consciousness that venerates figures of great wisdom, valor, and leadership, which serve as powerful archetypes in literature and culture. Ancient civilizations and their leaders are often mythologized in the same manner, representing the ideals and values admired by societies.
Thus, placing King Arthur among them elevates him to a status of a cultural hero that embodies the virtues and concerns of an entire civilization, and allows the poet to make a comment on the universal themes of heroism, leadership, and legacy.