When we walk into any container store, we see containers of various types and sizes.
If we look closely, even though the containers seem to have carved out space for us to keep stuff, the space inside them is still part of universal space everywhere.
By having the lid and walls, we temporarily get a feeling of dividing the space, but eventually, when the container is broken/recycled, we see the true picture of contiguous space.
In the same way, we all living beings too, are like containers, where we get a feeling that each of us is different due to covers made by our bodies. But, like container walls, bodies too are temporary and will eventually melt away, showing us a true nature of contiguous Brahman.
अहम् ब्रह्मास्मि (I am Brahman), from Brihadaranyak Upanishad, is one of the four mahavakyas, conveying exactly the same meaning that we saw in the above example.
All our fears, sorrows, hatred, ambitions, desires. attachments are due to we associating ourselves with the temporary bodies; once we get over it, and start identifying ourselves with the universal entity, all these will wither away, giving us eternal happiness and calm.
All the Best!