  The $X(3872)$, as the first and the most crucial member in the exotic
charmoniumlike $XYZ$ family, has been studied for a long time. However, its
dynamical origin, whether stemming from a $D\bar{D}^*$ hadronic molecule or the
first excited $P$-wave charmonium $\chi_{c1}(2P)$, remains controversial. In
this Letter, we demonstrate that the $X(3872)$ definitely does not result from
the mass shift of the higher bare $\chi_{c1}(2P)$ resonance pole in the
coupled-channel dynamics involving a short-distance $c\bar{c}$ core and the
long-distance $D\bar{D}^*$ channels. Instead, it originates from either the
$D\bar{D}^*$ molecular pole or the shadow pole associated with the $P$-wave
charmonium, which depends on the concrete coupling mode between the $c\bar{c}$
and $D\bar{D}^*$. In order to further exploit the nature of $X(3872)$, we
carefully investigate potential mechanisms that contribute to its pole width,
which suggests that the coupled-channel dynamics plays a critical role in
causing a noticeable discrepancy between the pole widths of $X(3872)$ and
$T_{cc}^+$. Interestingly, we bridge the quantitative connection among the
dynamics origin of $X(3872)$, its pole width and the properties of the
predicted new resonance. The precise measurement of the pole width of $X(3872)$
and the search for the new charmoniumlike resonance become highly significant
and can be anticipated in future LHCb, BESIII and Belle II experiments.
