Furthermore, the veneration of saints reinforces the idea of a supportive spirit…

Furthermore, the veneration of saints reinforces the idea of a supportive spiritual community. Saints are not distant figures but are regarded as part of an extended family of faith. Their feast days and stories are celebrated, reminding Catholics of the enduring power of faith and the transformative impact it can have on individuals and communities.
 
The veneration of saints in Catholicism serves as a source of inspiration, intercession, and a reminder of the profound connection between humanity and the divine. The brilliant lustre that the saints show through their lives is nothing other than the splendid glory of Christ Himself.
 
About their relics we place at the altar, The Directory on Popular Piety and the Liturgy explains this connection as such:
 
[Placing the relics of the Saints under an altar] signifies that the sacrifice of the members has its origin in the Sacrifice of the altar [the Eucharist], as well as symbolizing the communion with the Sacrifice of Christ of the entire Church, which is called to witness, even to the point of death, fidelity to her Lord and Spouse.
 
The saints are a proof of the infinite power of God and the work of the Holy Spirit in our midst: that power which is forever capable of calling forth eternal luminous souls from the pervasive dust and sin of our world.
 
We venerate the saints and celebrate their lives principally because – in the words of the Psalmist – “They are friends of the Lord, and they make known the glorious splendour of His Kingdom.” (Psalm 144:10-11)
 
And in celebrating them we are reminded that we are called to do the same: to be “salt to the earth, and light to the world”. (Matthew 5:13-16)
 
 
 
 
Reference:
 
https://catholicleader.com.au/people/why-do-we-venerate-the-saints/
https://churchlifejournal.nd.edu/articles/why-do-catholics-venerate-the-arms-and-tongues-and-blood-of-saints/