Al-Fatiha 1

(1)"In the name of Allah, the Entirely Merciful, the Especially Merciful."

... In the Name of God, the Compassionate, the Merciful

(2)"All praise is due to Allah, Lord of the worlds"

Praise be to God, is a predicate of a nominal clause, the content of which is intended to extol God
[by stating that]: He possesses the praise of all creatures, or that He [alone] deserves their praise.

God is a proper noun for the One truly worthy of worship; Lord of all Worlds, that is, [He is] the One Who owns all of creation: humans, jinn, angels, animals and others as well,
each of which may be referred to as a ‘world’; one says ‘the world of men’, or ‘world of the jinn’ etc.

This plural form with the yā’ and the nūn [sc. ‘ālamīn] is used to denote, predominantly, cognizant beings (ūlū ‘ilm).
The expression [‘ālamīn] relates to [the term] ‘sign’ (‘alāma), since it is an indication of the One that created it