  Several $X$ and $Z_{cs}$ exotic hadrons were claimed in the LHCb's amplitude
analysis on $B^+\to J/\psi \phi K^+$. The data shows that all the peaks and
also dips in the spectra are located at thresholds of seemingly relevant
meson-meson channels. While the LHCb analysis fitted the peaks with
Breit-Wigner resonances, threshold kinematical cusps might be the cause of such
structures. We thus analyze the LHCb data considering the threshold cusps. Our
model is simultaneously fitted to $J/\psi \phi$, $J/\psi K^+$, and $K^+\phi$
invariant mass distributions. The threshold cusps fit well all the $X$,
$Z_{cs}$, and dip structures. Our analysis indicates that spin-parity of the
$X(4274)$ and $X(4500)$ structures are $0^-$ and $1^-$, respectively. This is
different from the LHCb's spin-parity assignments ($1^+$ and $0^+$). The number
of fitting parameters can be significantly reduced by considering the relevant
threshold cusps. Our analysis shows that $D_s^{(*)}\bar{D}^{*}$ scattering
lengths are consistent with zero. This disfavors an explanation of
$Z_{cs}(4000)$ and $Z_{cs}(4220)$ as $D_s^{(*)}\bar{D}^{*}$ molecules, which is
consistent with lattice QCD via the SU(3) relation.
