Creo que "desde tu cuello" significa algo así como que la cabeza de la persona que habla está colocada sobre el cuello de la otra, o lo que es lo mismo, que una ve los acontecimientos a través de los ojos de la otra.

no por que me parece que esta hablandole a un mujer, como si hubieran estado abrazados cuando comenzo el siglo... no se es solo una idea....

From your hights I watched the stoical beginnings of this century.
My interpretation: she holds her head high, physical posture of a dancer, and mental attitude, specially when considering the previous sentence, 'con el mundo por montera' i.e. indifferent to people's opinion of her.

I believe she probably also carried her child, as well as the world, on her back. So the child saw the world literally from around her mother's neck. I wouldn't say from your neck, though I believe it would be correct, but "from your back" gives the idea that she had been seeing the world from her mother's back, whether literally or figuratively.
e.g. "Eight years in Buenos Aires and a whole life taking on the world. I saw the painful beginning of the century from your back."