Where are you from?

I invite you to take a guess given the obvious context clues.

I am only speaking to what the manifesto was proposing and nothing more.

You're speaking to what you imagined it was proposing not at all what it actually proposed not to mind when you take into account the wider writings of both Marx and Engels (as is necessary to truly understand the pamphlet that the manifesto is) both consistently differentiate between the state as an instrument of class rule and what we would call the government as an institution providing a necessary function of administration in advanced societies.

While the merely repressive organs of the old governmental power were to be amputated, its legitimate functions were to be wrested from an authority usurping pre-eminence over society itself, and restored to the responsible agents of society itself."

— The Civil War in France

State interference in social relations becomes, in one domain after another, superfluous, and then dies out of itself; the government of persons is replaced by the administration of things, and by the conduct of processes of production. The state is not 'abolished'. It dies out.

— Anti Duhring

I am also certain that you can provide nothing to back up the one world government claim (unless you choose to cherry pick and misinterpret harder than an evangelical) as it is simply not a position that Marx Engels or even any later Marxists have ever advocated for.