We present the first amplitude analysis of the semileptonic decay $D^0\to K^{-}{\pi }^0{e}^{+}{\nu }_e$ by analyzing $e^{+}{e}^{-}$ annihilation data corresponding to an integrated luminosity of 20.3 fb${}^{-1}$ collected at the center-of-mass energy of 3.773 GeV with the BESIII detector. A tiny $𝒟$-wave component of the $K_2^{*}(1430{)}^{-}$ accounting for $(0.157 \pm 0.056_{\rm stat} \pm 0.042_{\rm syst})\%$ of the $K^{-}{\pi }^0$ is observed for the first time with a significance of $7.9\sigma$ in addition to the dominant $𝒫$-wave component of $K^{*}(892{)}^{-}$ and the sub-dominant $K^{-}{\pi }^0$ $𝒮$-wave. The hadronic form factors of the $D^0\to K^{*}(892{)}^{-}$ transition are measured precisely as $r_V=V(0)/A_1(0)=1.432 \pm 0.050_{\rm stat} \pm 0.017_{\rm syst}$ and $r_2=A_2(0)/A_1(0)=0.786 \pm 0.037_{\rm stat} \pm 0.027_{\rm syst}$. The branching fraction of $D^0\to K^{*}(892{)}^{-}{e}^{+}{\nu }_e$ with $K^{*}(892{)}^{-}\to K^{-}{\pi }^0$ is measured to be $(7.445\pm0.061_{\rm stat.} \pm 0.048_{\rm syst.})\times10^{-3}$. Combining the measurements of the $D^0\to K^{*}(892{)}^{-}(K^{*}(892{)}^{-}\to K^{-}{\pi }^0){\ell }^{+}{\nu }_{\ell }$, lepton flavor universality is tested by the ratio $\mathcal{R}_{\rm LFU}=\mathcal{B}(D^0\to K^*(892)^-\mu^+ \nu_\mu)/\mathcal{B}(D^0\to K^*(892)^-e^+\nu_e)=0.928\pm0.020_{\rm stat}\pm0.012_{\rm syst}$ with unprecedented precision; no violation is found. Furthermore, isospin symmetry in the $K^{*}(892{)}^{-}$ decay is tested by $\mathcal R_{K^{*-}} =\mathcal{B}(K^*(892)^-\to K^- \pi^0)/\mathcal{B}(K^*(892)^-\to K_S^0 \pi^-)= 1.087\pm0.013_{\rm stat}\pm0.009_{\rm syst}$ for the first time using the latest measurement of $D^0\to K^{*}(892{)}^{-}{e}^{+}{\nu }_e$ with $K^{*}(892{)}^{-}\to K_S^0{\pi }^{-}$. Finally, the phase shift of the $K\pi$ $\matchcal{S}$-wave is extracted in a model-independent way, which sheds light on the nature of the lightest strange scalar meson $K_0^{*}(700)$.