Because their Timurid descent had better rulers and one of their Timurid ancestor had captured Delhi

Reasons for Mughals emphasizing their Timurid descent:
- Cultural and Political Legitimacy: The Timurid lineage provided the Mughals with a connection to the great Islamic conqueror Timur, also known as Tamerlane, which helped legitimize their rule and authority in the eyes of their subjects. This descent from a renowned Central Asian ruler gave the Mughals a sense of cultural and political legitimacy.
- Unity and Identity: Emphasizing their Timurid descent allowed the Mughals to create a sense of unity and identity among their diverse subjects. By highlighting their common heritage, the Mughals could foster a shared sense of belonging and loyalty among the different ethnic and religious groups within their empire.
- Historical Precedent: The Timurid dynasty had a rich history of cultural patronage and artistic achievements, which the Mughals sought to emulate. By associating themselves with this prestigious lineage, the Mughals could draw on the legacy of Timurid achievements in art, architecture, and literature to enhance their own cultural and intellectual prestige.
- Avoiding Negative Associations: Emphasizing their Timurid descent allowed the Mughals to distance themselves from the negative connotations associated with their Mongol ancestry. The Mongol invasions of the past had led to widespread destruction and loss of life in the region, and by focusing on their Timurid lineage, the Mughals could downplay any lingering resentment or fear towards their Mongol heritage.
In summary, by emphasizing their Timurid descent, the Mughals were able to establish a sense of cultural and political legitimacy, foster unity among their subjects, draw on a rich historical precedent, and avoid negative associations with their Mongol ancestry.